Power plant comprising a gas turbine and an internal-combustion engine compressor serving as a gas generator thereto



2,434,777 -COMBUSTION R. J. WELSH POWER PLANT COMPRISING A GAS TURBINE AND AN INTERNAL ENGINE COMPRESSOR SERVING AS A GAS GENERATOR THERETO 3 Sheets-Sheet 1 Filed Dec. 3, 1943 Jan. 20, 1948. R. J. WELSH 2,434,777

POWER PLANT COMPRISING A GAS TURBINE AND AN INTERNAL-COMBUSTION ENGINE COMPRESSOR SERVING AS A GAS GENERATOR THERETO Filed Dec. 3, 1943 3 Sheets-Sheet 2 Jan. 20, 1948. WELSH 2,434,777

POWER PLANT COMPRISING A GAS TURBINE AND AN INTERNAIrCOMBUSTION ENGINE COMPRESSOR SERVING AS A GAS GENERATOR THERETO Filed Dec. 3, 1943 3 Sheets-Sheet 3 Patented Jan. 20, 1948 POWER PLANT COMPRISING A GAS TUR- BINE AND AN INTERNAL-COMBUSTION ENGINE COMPRESSOR SERVING AS A GAS GENERATOR THERETO Robert'James Welsh, Rugby, England, asslgnor to- The English Electric Company Limited, London, England, a British company Application December 3, 1943; Serial No. 512,836

. In Great Britain September 30, 1942 This invention relates to a free-piston type compression-ignition internal combustion engine driven compressori. e. a device wherein a compressor, piston is directly connected to or combined with an internal combustion engine piston 1 Claim. (Cl. 60-13) instead of being driven thereby through con-.-

necting rods, cranks, crankshaftsused as a gas generator to supply to a prime mover (e. g. a gas turbine), as motive fluid, the exhaust from the engine cylinder (comprising "the products of the combustion in the engine. cylindermixed with charging or scavenging air-supplied to the engine by the compressor) with or without the admixture of air coming direct from the compressor.

According to the invention the exhaust gas, or at least some of the exhaust gas, from the prime mover is usedat least during operation at a light load-to heat the air drawn into the inlet to the compressor, thereby increasing the general cyclic temperature at low loads and tending, under these conditions, to prevent formation of inflammable deposits on parts of the system. Under any given set of conditions an increase in inlet temperature reduces the mass of gas drawn into the compressor cylinder at each suction stroke and therefore reduces the-possible power output of. the whole plant, which does not matter at light load; the invention permits the gas generator to operate over a wider range of powers than would otherwise be possible.

Means are preferably provided for deflecting the exhaust gases from the prime mover, or part of these gases, from the discharge outlet to the compressor inlet when the output of the plant falls below a predetermined value. Since the output is determined by the quantity of fuel supplied to the internal combustion engine cylinder per cycle, such deflecting means may be controlled by a member moving with the fuel regulator so as to be brought into action when the fuel supply per cycle falls below a predetermined minimum.

The exhaust gases, or a part of these gases, may be deflected so that they re-enter the system with the air drawn into the compressor, thereby heating the air by mixing with it either before or after reaching the compressor cylinder, this being simpler than passing the exhaust gases through a heat exchanger to heat the inlet air.

A plant including two opposed pistons reciprocable toward and away from each other in one cylinder, the engine operating on a two-stroke cycle, and incorporating the invention, is shown in the accompanying drawings, Figures 1,2 and 3, of which Figure 1 shows the gas generator in axial section while Figure 2 shows the turbine and governor partly in axial section; these two figures taken together constitute a single drawing of the whole plant, the conduits l4 and I6 and the link 3| of Figure 1 being connected to the similarly marked part of Figure 2, Figure 3 shows the whole plant in a single figure to a reduced scale and in external view.

The body of the internal combustion compressor comprises the engine cylinder I, the pair of compressor cylinders 2 at opposite ends thereof and the pair of buffer cylinders 3 at the extreme outer ends, while each free piston unit consists of one of the opposed engine pistons 4 reciprocating within the engine cylinder l, a compressor piston 5 reciprocating in one of the cylinders 2 and a buffer piston 6 reciprocating in one Of the cylinders 3. In the head of each of the compressor cylinders 2 is at least one inlet valve 12 which can put the cylinder 2 in communication with the inlet conduit I 4 and at least one discharge valve l3 which can put the compressor cylinder 2 in communication with the conduits l5 communicating with the annular space surrounding the ring of inlet ports la in the engine cylinder l. The latteris provided also with a ring of exhaust ports lb opening into an annular space with which communicates the exhaust pipe The reciprocating piston units are synchronised in the well known and usual manner by being linked by the pair of links I to opposite ends of the lever 8 having its mid point pivotally sup ported on the outside part of the engine cylinder I. Fuel can be injected into the cylinder l by fuel injectors 9 of conventional form supplied in usual manner through fuel pipe ll, the usual form of distributor l8 and the fuel pipes I 9, by the fuel injection pump ill of conventional form reciprocated by cam l l which is oscillated (in accordance with the'movement of the free piston units) by the lever 20, which is connected by link 2| to a point on one of the links 1; the quantity of fuel injected by each stroke of the injection pump I0 is determined in the usual manner by the position of its fuel rack Illa.

The conduit l6 connects the exhaust ports of engine cylinder I to the inlet to the turbine 25 which discharges through the exhaust pipe 28. The turbine shaft 25a drives-through gearing 2'l--a conventional form of centrifugal speed governor 28 the sleeve 28a of which latter acts through lever 29 turning on fixed pivot 30, link 3|, lever 32 turning about fixed pivot 33 and link 3! to position the fuel rack Illa of the fuel injection pump ill in accordance with the speed of the turbine so that in well known manner movement of governor weights 28b on an increase in turbine speed will act through movement ofsleeve 28a, lever'29, link 3| lever 32, link 34 andiuel racks Illa to decrease the quantity of fuel injected, while such movement on decrease in tur-.

The link 3i connecting the governor-actuated lever 29 (by way of lever 32 and link 34) with the fuel adjusting rack Ilia also extends to the slon, into the engine cylinder I.

jected fuel will ignite while the cam ll operates the fuel pump ill to inject into this compressed air (through the injection vaives 9) a quantity of fuel which is determined by the position of the fuel rack Ilia. During the outward stroke of pistons I and 5 following on the combustion of this fuel, the pistons 5 compress in the cylinders 2 the air previously drawn in through the inlet valves l2 which now close. When the free piston units come to rest at the end of this outward stroke, one'of the pistons 4 uncovers the inlet ports la and the air compressed in the cylinders 2 goes through the nonreturn valves l3 as shownby the arrows through the conduits i5 to the inlet ports la so scavenging the engine cylinder. The other piston 4 has also uncovered the exhaust ports lb so that the mixture of combustion products and scavenging air goes by way of conduit Hi to the inlet to the turbine 25 to serve as the motive fluid for this turbine and eventually is discharged by the turbine exhaust 26. The buffer pistons 6 during this outward stroke compress air in the buffer cylinders 3 until the pistonunits are brought to rest andwhen scavenging of the engine cylinder takes place the pressure in the bufler'cylinders 3 causes the piston units to rebound and return to the inner dead centre position, therebytrapping and compressing in the engine cylinder l some of the scavenging air while at the same time the compressor pistons 5 draw into the cylinders 2 a fresh charge of air through the non-return inlet valves l2 from the inlet pipes M. The operation so far described is well known and is described solely for the sake of completeness.

According to the invention a branch 40 from the turbine exhaust pipe 26 leads into the com pressor inlet i4, so that at least some of the. exhaust gas from the turbine is conveyed to where it can heat the air going into the compressor. The branch pipe 40 is controlled by valve 39.

lever 36 which turns about fixed pivot 31 and is connected by link 38 to the diverter valve 39. As the link 3| moves to decrease the fuel injected, the valve 39 opens whereby some of the hot exhaust gas is deflected from the turbine exhaust pipe 26 and goes as shown by the arrows through branchpipe 40 to pipe l4 whence it is drawn with the incoming airmixing with this ,airand raising its temperatureinto the compressor cylinders 2 and thence, after compres- Although this reduces the percentage oxygen content of the inlet air and hence of the charge entering the engine cylinder, such reduction is not so important at light load conditions and moreover under such conditions the percentage oxygen content in the exhaust gas is at a maximum and hence the dilution effect on the air entering the inlet is at a minimum.

What I claim as my invention and desire to secure by Letters Patent is:

A power plant comprising, in combination, a gas turbine, a free-piston type compression-ignition internal combustion engine driven compressor, a conduit connecting the exhaust gas turbine, a fuel supply regulator for the engine,

a branched exhaust pipe from the turbine, one branch of this pip leading into the compressor inlet, a diverter valve controlling said branch and means operatively connecting together said governor, said fuel regulator and said diverter valve in a sense to decrease the fuel supply on an increase in turbine speed and to divert turbine exhaust gas into the compressor at low values of fuel supply.

3 ROBERT JAMES WELSH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,652,122 Homing Dec. 6, 1927 1,816,345 Secor July 28, 1931 1,982,146 Sloan Nov. 27, 1934 2,147,935 Steiner Feb. 21, 1939 2,182,063 Steiner Dec, 5, 1939 2,303,794 Pateras-Pescara Dec. 1, 1942 FOREIGN PATENTS Number Country Date 12,735 Great Britain May 31, 1906 346,108 Great Britain Apr. 9, 1931 

